<!DOCTYPE html>
<html lang="en">

<head>
    <meta charset="UTF-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
    <style>
        fieldset {
            width: 500px;
            height: 600px;
        }
    </style>
</head>

<body>
    <!-- 
        fieldset和legend配合多个表单控件根据需求来分组
        fieldset定义组类， legend定义组标签
     -->
    <form action="">
        <fieldset>
            <legend>用户注册扩展信息</legend>
            姓名： <input type="text" placeholder="请输入账号"><br> 密码： <input type="password" placeholder="请输入密码">

        </fieldset>
    </form>
</body>

</html>